ltdan12a

Have an '89 944 that will be getting run in ES, SCCA Solo....

What's the biggest size R-compound that people are running on the phone dials?

PedalFaster

AP1 S2000s have slightly smaller wheels (16" x 6.5" F, 16" x 7.5" R compared to the 944's 16" x 7" F, 16" x 8" R), but can still fit 245s in front and 275s in back, so at least those sizes would fit on a 944.

Whether you want to run those sizes is another story. When I ran a 968, I ran 245 F / 275 R, but if I did it again, I would try a square setup (245 or 275 all around). I had a giant front bar, though, so a staggered setup might be best with a smaller or stock front bar.

ltdan12a

I THINK I can do a 245 on a square setup... the phone dials are 15x7, so I have a junk 245 hoosier coming to check how bad they will be pinched on the wheel... Makes me wanna just say eff it and step up to ST* or street prepared with the thing...

PedalFaster

I must have been thinking of some other phone dials. :P

Hoosiers are meant to be stretched over skinny wheels. D Stock Integra Type Rs sometimes run 275s on the stock 15" x 6" rims, so 275s should definitely fit on your rims as well. Whether they'll fit in your fenders is a different question.

Autocrosser#73

Reviving an old post here rather than starting a new one. I am wondering what the widest street tire I can fit on my stock 18x7.5" Boxster S wheels. TireRack says only a 225 since its tread would be 8.4" wide, almost an inch wider than the 7.5" rim.

I know that street tires have a softer sidewall than R-compound race tires do, so pinching a wide, street "140+ rating" tire would not have the same benefit. What do you think would be the best size tire for these aforementioned wheels?

sjfehr

There's a point of diminishing returns, where distortion of the tire to stretch it onto the rim gives less overall grip than a narrower tire that fits.

Autocrosser#73

I agree about the diminishing returns of a tire that is too wide. Is an 8.8" wide tire (235/40) too much for my stock 7.5" twist wheel?

racer

At somepoint the issue might be how willing someone is to mount an "extra" wide tire on too narrow a rim. imho, AX#73, a 1.3" difference doesn't seem like much at all.

As to the OP, ltdan, I've been thinking about running EStock as well.. I'd recommend a 205 width for you

ltdan12a

The more the merrier dude!!!

Oh, and I already have a tracking number for the 275's... lol

Dan
(installing Koni's as we speak)

gomarlins3

I am trying to determine the widest tire I can get on my 1998 Boxster on the OEm 16" wheels for autoX. I have gone through all 19 pages of threads and find many threads related to my question, but none for my year and wheel size.

Can I fit a 225/50ZR-16 on the front? What would be the down side to running that size on all four corners?

racer

A 98 boxster came with 6 and 8 x 16 wheels iirc. 225 would be pinched on a 6" rim. 205 is a more natural fit.

Considering Boxsters also came with 7" front and 8.5" rims, you might consider locating a set of 17's for use. Prices tend to be in the $400-600 range for a set of rims. 17" rims also allow for more tire selections,

I know several folks who ran a square set up (245s in most cases) without issue. Running 225s would likely be ok as well. It would certainly help dial out some of the inherant understeer.

knfeparty

I did some research and heard from a guy that saw firsthand a late NA 944 with factory clubsport wheels and option code, so that's what I ran on my car.

I had 225 width BFG R1s on the fronts and 245s in the rear on my phone dials, and when I shifted over to the clubsports (which are 9" wide rears IIRC) the 245s were almost too small. You could probably fit a 285 on that thing.

225 and 245 was a good-handling setup on phonies, but I think 245 square would be better strictly for autocross. I did rub a bit at full lock though.

racer

I'd re-read the scca rulebook about what constitutes a "stock" wheel. Clubsports were not available on the base 944 and scca might not allow them. 7x15s were the standard wheel with either 7/8 x15 or 7/8x16s an option on the base 944.

A square set up allows you to maximize tire life. A staggered set up may or may not be quicker.